The present invention relates to a method for removal of organic contaminants from contaminated air and water, and more specifically, to a method of separating halogenated hydrocarbons from fluid feedstreams with polyphosphazene membranes. Fluid feedstreams include both gas and liquid feedstreams.
Various purification techniques for removing organic contaminants from such feedstreams as ambient air, groundwater, or eluants from chemical processes, are known. Conventional air sparging and carbon adsorption techniques have been used to remove volatile organics from groundwater. The problems with both techniques are obvious, with air sparging merely distributing contaminants (albeit in lower concentrations) to the air, and carbon adsorption techniques generating large masses of now contaminated carbon, which in turn must be disposed.
Membrane separation has been used, for example, in the desalination of sea water and offers advantages of removing and collecting waste substantially in a single step and in a relatively small volume as compared to benign carbon from carbon adsorption techniques. However, many organic polymer membranes do not survive when exposed to organic solvents.
U.S. Pat. No. 4,170,204 provides examples of polyphosphazene membranes for the limited application of separating acid gases from gaseous mixtures containing nonacid gases, such as, gaseous hydrocarbons.
U.S. Pat. No. 4,749,489 issued June 7, 1988 and assigned to the present assignee discloses polyphosphazene membrane fabrication techniques and polyphosphazene membranes for the separation of selective components from a fluid feedstream.
An object of the present invention is to provide a new and improved method of separating organic contaminants from fluid feedstreams. It is a feature of this invention to have a membrane which permits rapid, selective separation of organic contaminants from feedstreams. An advantage of this invention is the one step process of simultaneously removing and collecting the contaminant in a relatively inexpensive and efficient manner compared to decontamination techniques found in the prior art.
Another object of the present invention is to provide an efficient and economical method for separating halogenated hydrocarbons from fluid feedstreams using a membrane. A feature of this invention is the recognition that the polyphosphazene membrane used is resistant to the harsh environments often found in environmental clean-up scenarios and recycling operations in chemical processes. As such, an advantage of this invention is the efficiency of the invented process in harsh environments.
Yet another object of the present method is to incorporate the pervaporation process in the removal of halogenated hydrocarbons from liquid feedstreams using a polyphosphazene semipermeable membrane. It is a feature of this process to exploit the affinity that the semipermeable membrane has for halogenated hydrocarbons, such as halogenated hydrocarbons, for example, methylene chloride, carbon tetrachloride and chloroform. The advantage confered in this process allows for separation of halogenated hydrocarbons from aqueous feedstreams in an efficient manner.